200540281 (1) 九、發明說明 【發明所屬之技術領域】 本發明係關於質輕且比剛性高的鎂合金，特別係關 於壓鑄用鎂合金以及使用此壓鑄用鎂合金的鎂壓鑄製品 【先前技術】 在被大量地使用的合金中，鎂合金是最質輕且比剛 性高的合金，以筆記型電腦、手機爲首，被使用於攜帶 型電動器具等之中的鑄造用Mg合金，幾乎爲AZ91合金 。此AZ9 1合金，強度、耐蝕性、成形性等方面優異，作 爲均衡性佳的鑄造用合金，而廣泛地被使用在壓鑄用， 但是並不適用於被要求高拉伸、彎曲、耐熱性的機械特 性之汽車、機車等的用途中。因此，對於這些用途，通 常是使用減少 A1量來改善拉伸性之 AM 60系合金或 AM50系合金。 近年來，隨著對於汽車零件的輕量化要求的提高， 同時更靠近引擎的蓋類也要Mg合金化，所以賦予耐熱性 能的新合金的開發，熱烈地進行（例如參照專利文獻1 )。 根據此習知技術的合金，係改良AM50合金或AM60合 金而成的合金；以 A1 : 2〜9重量。/〇、S r : 0.5〜7重量°/〇 作爲基質，理想爲作成A1 ·· 4〜6重量％及A1 : 4.5〜5.5 重量％且Zn : 0.35重量°/。以下（AM合金標準）。又，關於 根據前述習知技術所作成的合金和AZ系合金的比較，例 -5 - 200540281 (2) 如記載於非專利文獻1。第]7圖係表示被記載於此文獻 中的比較內容的圖。 進而，在專利文獻2中，顯示出藉由Si、RE等來嘗 試改良特性的例子；作爲一例，表示以R E : 0 · 1〜4重量 %、S i : 0.7〜5重量％、Μ η : 1重量％以下、Z r : 1重量％ 以下、Ca : 4重量％以下、A1 : 1 0重量％以下、Zn : 5重 龜 量°/〇以下、Ag : 5重量。/。以下，來構成成分的例子。 、 【專利文獻1】日本特表2003-517098號公報 【專利文獻2】日本特開平9-316586號公報 【非專利文獻 1】pegureryutu、Balil共著「 Development of Creep Resistant Mg-Al-Sr Alloys」 Magnesium Technology 2001(TMS) 【發明內容】 •(發明所欲解決之課題） 但是，前述習知的合金（改良AM50合金或AM60合 金而成的合金），存在以下的課題。 第1 7圖的下段係表示前述習知技術的合金（以下適 當地稱爲習知合金）的一例，與AZ91合金比較，室溫（常 溫）下的拉伸強度，大約低15%。而在175 °C時的拉伸強 度，雖然被改善7 %程度，但是室溫、1 7 5 °C下的拉伸率 低。潛變特性値等，確實被改善，但是材料實際使用時 ，由於係暴露在自室溫開始至1 7 5 °C爲止的高溫的環境中 ，所以無法無視於室溫下的物性。前述習知技術，並未 -6- 200540281 (3) 考量此點，而無法防止在室溫下的強度的降低。 本發明的目的在於提供一種壓鑄用鎂合金以及使用 此壓鑄用鎂合金的鎂壓鑄製品，不會招致室溫強度的降 低，並能夠提升高溫潛變性能。 (解決課題所用的手段） * 爲了達成前述目的，根據第1發明的壓鑄用鎂合金 、 ，其特徵爲：對於鋁6.0〜11.0重量％、鋅0.1〜2.5重量 °/。、錳0.1〜0.5重量％之AZ91系合金，作爲結晶微細化 劑，添加銻及鈣之中的至少其中一方、及緦。 就本案的第1發明而言，係將成爲基質的合金，設 爲含有鋁6.0〜11.0重量％、鋅0·1〜2.5重量％、錳0.1 〜0.5重量％之ΑΖ91系合金，而對於此合金作成添加了 Sb、Ca、Sr的組成。藉由將基質設爲ΑΖ91系合金，能 •夠防止如AM60系合金般的室溫的強度特性降低的情況 。而且，藉由對此AZ91系合金添加Sb、Ca、Sr來作爲 結晶微細化劑，改良合金組織來使結晶粒徑尺寸微細化 ，而能夠得到與以高溫潛變性能且耐熱性鎂合金聞名的 A S 2 1合金同等的優異特性。結果’不會招致室溫強度的 降低，並能夠實現高溫潛變性能已經提高的合金。 爲了達成前述目的，根據第2發明的壓鑄用鎂合金 ，其特徵爲：對於已經在鋁6.0〜Η·〇重量％、鋅〇.1〜 2.5重量％、錳0.1〜〇·5重量％之AZ91系合金中，添加 了矽0.1〜1 · 5重量％、稀土族〇 · 1〜1 · 2重量％、及鉻〇 . 2 200540281 (4) 〜0.8重量％之中的至少其中之一而成的合金，作爲結晶 微細化劑，進而添加銻及鈣的至少其中一方、及鋸。 就本案的第2發明而言，係將成爲基質的合金，亦 即對於鋁6.0〜Π . 0重量％、鋅0 · 1〜2.5重量％、錳〇 .；[ 〜0.5重量％之所謂的ΑΖ91系合金，添加矽〇·ι〜1.5重 量％、稀土族〇 · 1〜1 .2重量％、及鉻0 · 2〜0.8重量％之中 的至少其中之一而完成基質合金，也就是加入一面維持 ‘ 成形性、常溫強度，一面提升高溫潛變性能的元素。而 且，藉由對此ΑΖ9 1系合金，作爲結晶微細化劑，進而添 力口 S b、C a、S r，改良合金組織，能夠使結晶粒徑尺寸微 細化。 與前述本案的第1發明相異，在基質合金側，添加 了矽、稀土族、鉻的其中之一；這些合金，會進入可說 是八291系合金的弱點亦即粒界生成物？^17人112(冷相）、 •或若添加Ca便會生成的Al2Ca結晶的間隙內，而分開這 些相，因而能夠改善強度。但是，若添加過度，則由於 會招致成形性惡化，所以理想爲添加至：矽1 . 5重量％、 稀土族1 · 2重量％、鉻〇 · 8重量％爲止。結果，能夠確實 地保持本發明的合金的特徵亦即成形性，並更加提升耐 熱潛變特性。 第3發明，係如前述第1發明或第2發明，其中作 爲前述結晶微細化劑，添加銻〇〜1.5重量％及鈣0.2〜 3 · 5重量％之中的至少其中一方、及緦0 · 1〜1 . 5重量％， 其他成分則爲不可避免地被包含。 -8 - 200540281 (5) 就本案的第3發明而言，藉由將銻、鈣及緦的添加 量，設爲銻0〜1 . 5重量％、鈣0.2〜3 · 5重量。/。、緦0 · 1〜 1 . 5重量％，能夠確實地使結晶粒徑尺寸在2 0 # m以下’ 而能夠得到與以高溫潛變性能且耐熱性鎂合金聞名的 A S 2 1合金同等的優異特性。結果，不會招致室溫強度的 降低，並能夠確實地實現高溫潛變性能已經提高的合金 〇 、 爲了達成前述目的，根據第4發明的鎂壓鑄製品， 其特徵爲··使用壓鑄用鎂合金，被進行壓鑄鑄造而構成 而該壓鑄用鎂合金，係對於鋁6.0〜1 1 . 〇重量％、鋅 0.1〜2.5重量。/◦、錳〇.1〜〇.5重量％之AZ91系合金，作 爲結晶微細化劑，添加銻及鈣之中的至少其中一方、及 緦而成的合金。 • 就本案的第4發明而言，作爲在鎂壓鑄製品中所使 用的合金，係使用對於含有鋁 6.0〜1 1 . 0重量％、鋅 〇 . 1 〜2.5重量。/〇、錳0.1〜0.5重量％之所謂的AZ91系合金 ，添加了 Sb、Ca、Sr的組成之合金。藉由將合金的基質 設爲AZ91系合金，能夠防止如AM60系合金般的室溫的 強度特性降低的情況。而且，藉由對此AZ91系合金，添 加Sb、Ca、Sr，來作爲即使爲了壓鑄而再熔解也不會損 害效果之結晶微細化劑，不會損害熔湯流動性，改良合 金組織來使結晶粒徑尺寸微細化，同時能夠得到與以高 溫潛變性能且耐熱性鎂合金聞名的AS2 1合金同等的優異 200540281 (6) 特性。結果’使用不會招致室溫強度的降低且高溫潛變 性能已經提高的合金，能夠製造出成形性佳的壓鑄製品 〇 爲了達成前述目的，根據第5發明的鎂壓鑄製品， 其特徵爲：使用壓鑄用鎂合金，被進行壓鑄鑄造而構成 « 而該壓鑄用鎂合金，係對於已經在鋁6.0〜11.0重量 i %、鋅0.1〜2.5重量％、錳〇·ΐ〜〇.5重量％之AZ91系合 金中，添加了矽0.1〜1.5重量％、稀土族〇·1〜1.2重量°/〇 、及鉻0·2〜0.8重量％之中的至少其中之一而成的合金 ，作爲結晶微細化劑，進而添加銻及鈣之中的至少其中 一方、及緦而成的合金。 與前述第2發明相同，藉由在基質合金側’添加了 矽、稀土族、鉻的其中之一；這些合金，會進入可說是 • ΑΖ91系合金的弱點亦即粒界生成物Mg17Al/3相）、或 若添加C a便會生成的A 12 C a結晶的間隙內，而分開這些 相，因而能夠改善強度。但是，若添加過度’則由於會 招致成形性惡化，所以理想爲添加至：矽1 . 5重量％、稀 土族1 .2重量％、鉻〇 · 8重量％爲止。結果’能夠確實地 保持本發明的合金的特徵亦即成形性，並吏加提升耐熱 潛變特性。 第6發明，係如前述第4發明或第5發明’其中使 用壓鑄用鎂合金，被進行壓鑄鑄造而構成； 而該壓鑄用鎂合金’係使用作爲前述結晶微細化劑 -10- 200540281 (7) ，添加鍊0〜1 · 5重量％及鈣〇 · 2〜3 . 5重量％之中的至少 其中一方、及緦0 · 1〜1 · 5重量°/〇，其他成分則爲不可避 免地被包含而成的合金。 就本案的第6發明而言’藉由將銻、鈣及緦的添加 量，設爲鍊0〜1 · 5重量％、錦〇 · 2〜3 · 5重量％、總0 · 1〜 1 . 5重量°/。，能夠確實地使結晶粒徑尺寸在2 0 # m以下， ’ 而能夠得到與以高溫潛變性能且耐熱性鎂合金聞名的 - A S21合金同等的優異特性。結果，使用不會招致室溫強 度的降低，且高溫潛變性能已經確實地提升的合金，能 夠成形性佳地製造壓鑄製品。 【實施方式】 (實施發明的最佳形態） 以下，一邊參照圖面一邊說明本發明的一實施形態 〇 本發明的發明人，如前所述，根據不會如習知合金 般地招致室溫強度的降低，並提升高溫潛變性能的觀1占 ’針對一面維持AZ9 1合金的優異特性一面改善高溫潛變 特性之壓鑄用鎂合金以及壓鑄製品進行各式各樣的檢討 。以下，依序地說明其思考方式及檢討結果。再者，文 中的％表示，全部是表示重量％。 (1)結晶粒徑尺寸的微細化 首先，本發明的發明人，以AZ9 1合金壓鑄品的特性 200540281 (8) 改善爲目標’進行檢討。將A Z 9 1合金壓鑄鑄造後的結晶 粒徑尺寸，大約爲40#m，與大約爲200〜300/im之通 常的重力鑄造的情況比較，結晶粒相當微細化。因此， 被使用在習知重力鑄造中的結晶微細化劑，在壓鑄鑄造 中被視爲不需要。本發明的發明人，刻意將微細化劑添 加在壓鑄合金中，嘗試以此合金的鑄錠來進行壓鑄成形 〇 • 各種微細化劑之中，如六氯乙烷般，即使微細化效 果高，在添加時會發生氯氣；或是如金屬Na般的在處理 上會伴隨著相當的危險。作爲用於壓鑄且即使再熔解也 不會損害效果的微細化劑，在本發明中，選擇Sb、Ca、 Sr，並進行複合添加的檢討。 最初，關於A Z 9 1合金和將S b 0 · 5 % + C a 0 5 % + S r 0.5 % 添加入A Z 9 1中而成合金，利用爐內冷卻法測量熔點。由 " 該結果可知’添加了 Sb、Ca、Sr的合金，與AZ91合金 比較，熔點稍低（參照第1圖）。關於其他的元素，也分別 添加1%在A Z91合金的熔湯中’來測量其熔點。由該結 果可知’連同各元素少量添加的情況，也是維持其熔點 或是下降（參照第2圖）。將各自的熔湯再度熔解，分別注 入鑄模內，確認了所有的熔湯的流動性（在應用於壓鑄製 品的情況，相當於壓鑄成形性）完全沒有問題，是良好的 。再者，作爲RE源，使用MM(混合稀土金屬）。 接著，在銘塗層後的鐵堪堝中，熔解AZ91合金3kg ，保持在6 8 0 °C之後，添加規定量的C a和S r，然後利用 200540281 Ο) 柄勺每次1 0 0 g快速地澆鑄在預先溫熱成1 0 0 °C的管狀金 屬模（管壁厚度3mm、內徑32mm0、深度53mm)中，而 作出試料。試料在中間部往橫向切斷，並爲了使結晶粒 界鮮明化，進行4〗0 °C、2小時的熔體化處理，再硏磨成 鏡面之後，利用6%苦味酸乙醇溶液進行蝕刻，並用顯微 鏡檢查。結晶粒徑尺寸，係利用鋼鐵JIS的結晶粒度測 量法的切片法來求得。 '第3圖係表示將Sb和Ca添加在AZ91合金中的添 加結果。由此圖可知：添加銻的情況，效果較小，但是 若複合添加銻和鈣，則具有大致與添加鈣同等的效果。 第4圖係表示在已經複合添加的熔湯中，添加Sr的情況 的例子；利用添加 SrO. 6%以上，結晶粒尺寸變成20 // m 以下。關於將 Si、RE、Zr分別添力卩0.5〜1 ·0%在 AZ91 合金中而成的合金，也進行同樣的試驗，就結晶粒尺寸 而言，也可以得到幾乎相同的結果。雖然分散出現Si、 RE、Zr各自特有的結晶，但是就全體的結晶粒尺寸而言 ’並沒有變化。 第5圖係表示改變S b、C a、S r的各種添加情況，調 查其與結晶粒徑尺寸的關係的結果的一例。再者，此情 況之所謂的 AZ合金，除了 AZ91合金以外，係指 A Z 9 1 + 〇 . 5 % S i 合金、AZ91+0.5°/〇RE 合金、AZ91+0.5%Zr 合金。如第 5圖所示，可知：在 Sb0.5%、Ca0.5〜3.0% 、S r〇 . 1〜1 . 5 %的範圍內，進行複合添加時，在虛線所包 圍的範圍內，則能夠在2 0 // m以下。 -13- 200540281 (10) 再者，本發明的發明人，根據另外的實驗，得知： 關於前述s b及c a ’即使沒有添加兩者’但是只要添加 S b ·· 0〜1 . 5 %及C a : 0 · 2〜3 · 5 %的至少其中一方，便可以 得到與前述虛線所包圍的範圍同樣的微細化效果。因此 ，爲了得到此微細化效果，只要複合添加Sb : 〇〜1.5% 及 Ca: 0.2〜3.5 %之中的至少一方、及Sr: 0.1〜1.5%便 可以。 將Sb、Ca及Sr添加在AZ91合金中而成的合金，對 其進行壓鑄成形，當與AZ9 1合金比較時，壓鑄成形品的 結晶粒徑尺寸，與澆鑄在管狀金屬模內時的結晶粒徑尺 寸大致相等；另一方面，相對於 AZ91 合金之 AZ9 1SbCaSr合金的結晶粒徑尺寸比，即使是在相異的鑄 造·成形條件下，可知大約微細化成W3 (參照第6圖）。 以往，關於壓鑄品，由於結晶粒微細化劑係被視爲無用 的，故此爲新的創見。 如此的結晶粒尺寸的微細化，由於粒界的網絡表面 光滑細緻，材料強度增加，且析出在粒界的yS相的厚度 變薄，由於成爲腐蝕原因之容易在粒界生成的粗大的金 屬間化合物，變成不易生成，所以能夠提高腐蝕性。將 Si、RE、Zr添加在AZ合金中而成的合金的強度、耐蝕 性提高的情況，此與防止/3相等進入粒界的金屬間化合 物之間來防止粗大化，其結果將帶來特性提高的情況， 可以說是非常相似的作用機構。 200540281 (11) (2)室溫強度及拉伸特性和熔湯流動性 接著，本發明的發明人，依據前述（1 )的結果，檢討 如前述般的AZ91合金、及將Si、RE、Zr添加在AZ91 合金中而成的合金、及進而添加Sb、Ca、Sr而成的合金 (以下’適當地簡稱爲「S b、C a、S r添加合金」）的室溫 強度特性及室溫拉伸特性。 使用第7圖所示的合金鑄錠，利用冷式壓鑄成形機 •，成形溫度（熔解爐溫度）6 5 0 °C，並使用1.5mm厚、B5 尺寸的平坦的試驗金屬模，以金屬模溫度2 0 0 °C的狀態下 ，分別成形80枚。將成形板5枚橫方向分割3等分、縱 方向分割2等分，而作成的6枚小片，利用水置換法來 測量其密度，再根據另外分析出來的成分値和化學便覽 記載的原子密度表，加以累計所求得的理論密度.，計算 模內的充塡率。進而，從成形板5枚’切出常溫拉伸試 驗片，再利用英式拉伸試驗機（i n s tΓ 0 n te n s丨1 e t e s t e r)測量 室溫下的拉伸強度、拉伸率（拉伸値）。 第8圖係表示壓鑄成形後的前述試驗板的充塡率（本 發明組成的平均値）。由此圖可知’若添加Sb、Ca、Sr， 充塡率提闻。 第9圖係表示壓鑄成形品的室溫拉伸強度。又’合 倂表示壓鑄試驗片進行4 1 0 °C、2小時熔體化處理後的測 量結果。如該圖所示可知’ as-cast的情況，Sb、Ca、Sr 添加合金比AZ91合金高7%左右的値。又’ AZ91合金’ 若進行熔體化處理，則強度下降’而根據試驗片觀察的 -15- 200540281 (12) 結果，散見氣泡，此被認爲是使物性降低、充塡率下降 的原因。而根據添加了 S b、C a、s r之本發明的實施形態 的合金，即使進行熔體化處理，強度不會降低，也沒有 觀察到氣泡。 又，將拉伸率表示於第10圖中，Sb、Ca、Sr添加合 金大致與AZ91合金相同。可知若將Sb、Ca、Sr添加在 AZ91合金中’在壓鑄時，沒有氣泡捲入，由於提高充塡 * 率同時提高拉伸強度，所以壓鑄成形性被改善。 另一方面，對於被添加側的AZ91合金，本發明的發 明人，也就各成分進行檢討；就A1而言，若比6%低， 得知將無法得到前述室溫拉伸強度的改善效果。因此， 爲了改善室溫拉伸強度，A1的含量比率，判斷設爲6%以 上是適當的。 關於S i ' RE、ΖΓ的添加效果，如前所述地以目視確 • 認熔湯流動性來決定前述上限。若超過這些上限，則黏 性增加，確認了將對熔湯流動性產生不良影響。又，下 限値’則是觀察添加而成的合金的室溫拉伸強度，以強 度被改善的量作爲下限値。第1 1圖係表示此時的添加量 和室溫拉伸強度之間的關係。添加改善效果，平均是 + 12%。 根據以上的結果，本發明的發明人，判斷將已經對 於 A 1 : 6 〜1 1 · 〇 %、Ζ η : 0 · 1 〜2 · 5 %、Μ η : 0 · 1 〜0 · 5 % 之 ΑΖ9 1合金，添加了規定量的Si、RE、Zr而成的合金， 作爲基質合金是適當的。將這些基質合金總稱爲AZ91系 200540281 (13) 合金，關於各圖表，也是表示其全體的平均値。 (3)高溫潛變特性 接著，本發明的發明人，依據前述（1 )、（2 )的結果’ 檢討Sb、Ca、Sr添加合金的高溫潛變特性。 由壓鑄成形品5枚，切出試驗片，並利用定速式高 溫潛變試驗機，求出在1 7 5 °C時的潛變資料。再者，爲了 * 進行比較，關於通常的AZ91合金或其他的AZ系合金， 也進行同樣的測量。 在第11圖、第12圖及第13圖中，表示在175 °C時 的定速法高溫潛變試驗的結果。 第Π圖係表示應變速度和流動應力的關係。將Sb、 .Ca、Sr添加在AZ91合金中所得到的本實施形態的Sb、 Ca、Sr添加合金，與AZ91合金比較，在各應變速度下 • ，提高1 5〜3 0%流動應力，可知耐潛變性變高。 第12圖係表示潛變拉伸率的資料。AZ61合金以及 A Z91合金，會由於潛變速度的不同，拉伸率會有在25% 以下的情況；相對於此，Sb、Ca、Sr添加合金，不論應 變速度爲何’拉伸率皆在3 5 %以上。 第13圖係爲了與其他的合金比較，在日本鎂協會的 資料庫的圖表上，記載這些結果所得到的圖。協會的測 量方法爲定應力法。不論是何種方法，原理上皆是評價 相同物性的方法。再者，也一倂表示其他合金在1 7 5 t：時 的文獻資料。再者，圖中，「Mercer」係表示根據文獻 -17- 200540281 (14) 「W.E.MercerII“ Magnesium Die Cast Alloys for Elevated Temperature Applications’，，SAE Paper No.900788, SAEWarrendale，PA，U.S.A，1 990.」的資料；「長岡技大 」則是表示根據文獻「後閑康裕、鎌土重晴、武田秀他 著：“ Mg-Zn-Al-Ca-RE系合金壓鑄材的顯微組織及高溫 強度特性”輕金屬學會第1 0 3回秋期大會演講槪要集！5-1 6，P . 3 7 5」的資料。 • 第1 3圖所示的本發明的發明人的潛變試驗與日本鎂 協會的潛變試驗的測量條件，表示於第1 4圖中。 第13圖中的長岡技大的ZACE054 1 1合金，與AS21 交叉而立起。其他的資料係關於Mercer的基本的合金的 資料，能夠看淸耐熱鎂合金的 AS41、AS21、AS42的耐 潛變性，位於何種水準。 根據本實施形態的S b、C a、S r添加合金，係位於 AS21合金的潛變曲線的延長線上，在時的耐潛變 性可以被認爲與A S 2 1相等。亦即，可知利用將S b、C a 、S r添加在A Z 9 1系合金中，可以得到具有與高溫潛變 性高的A S 2 1以上的高溫潛變性之合金。 再者，本發明的發明人，與前述相同，不是檢討Sb 、Ca、Sr的添加量，而是也另外檢討被添加側的AZ91 系合金的成分對於室溫拉伸強度的影響；得知若A1的含 量比率若超過1 1重量％，則拉伸率的劣化將會超過1 %， 所以爲了提高高溫潛變性，A1的含量比率，設爲1 1重量 %以上是適當的。 200540281 (15) (4)耐蝕性 A Z 9 1合金係在M g合金中的耐蝕性優異的合金；本 實施形態的合金，作爲基質合金，在A Z 9 1合金中添加了 S i、R E、Z r，而作爲微細化劑，則是添加了新的元素s b 、C a、S r。若因而造成耐鈾性大幅地劣化則不耐實用。 因此，本發明的發明人，藉由對本實施形態的AZ系的 Sb、Ca、Sr添加合金和通常的AZ91合金進行鹽水噴霧 •試驗，進行耐蝕性的確認。 鹽水噴霧試驗的槪要係如下述般地進行。首先，作 爲原料鑄錠，係使用第1 5圖所示的鑄錠。關於壓鑄成形 ，係對試驗合金 A、B，以 6 2 0 °C、6 5 0 °C、6 8 0 °C各成形 溫度（熔解爐溫度）進行壓鑄成形，並作成板狀。又，作爲 鹽水噴霧試驗用試樣形狀，成形板的厚度設爲0.7mm， 並切出95mm X 130mm的形狀。作爲前處理條件，並不進 行化成處理，而是以丙酮擦拭表面。 作爲試驗方法，使用腐蝕鹽水噴霧試驗機（Siiga試驗 機股份有限公司製造），試驗槽內溫度設爲3 5 °C、噴霧壓 力設爲〇.〇98MPa(Ikgf/cm2)。以此條件連續噴霧2小時 之後，以流水沖洗試料後，放置1 6小時，再藉由目視以 五階段評價「幾乎沒有腐蝕-〜5」、「稍微腐蝕+〜4」 、「有腐蝕++〜3」、「全面地腐蝕+ + +〜2」、「全面顯 著地腐蝕〜1」來評價腐蝕發生的程度。 第16圖係表示其結果。如第16圖所示，根據本實 施形態之AZ91系且添加了 Sb、Ca、Sr各0.5%的合金， 200540281 (16) 係前述「有腐蝕〜3」，通常的AZ91合金也是「有腐 1虫+ +〜3」。亦即，關於腐蝕性，前述兩種合金之間沒有 大的差異’可知本實施形態的Sb、Ca、Sr添加合金，也 確保有與通常的AZ合金大致相等的耐蝕性。 如前所述’若根據本實施形態，能夠得到一種壓鑄 用鎂合金’一面確保良好的壓鑄成形性及腐蝕性，一面 具有與AZ91合金同等的室溫拉伸強度，並具有高溫潛變 J 性。根據本實施形態的合金，對於能夠發揮輕量化效果 的變速器蓋、承油盤、或是車用空調活塞部外殼、氣囊 蓋、引擎蓋等的用途，作爲涵蓋自室溫區域至高溫區域 爲止的錶壓銳製品’是特別有用的。 【發明之效果】 若根據申請專利範圍第1項〜第6項的發明，由於 作成對A Z 9 1系合金添加了 S b、C a、S r的組成，所以能 夠防止室溫的強度特性降低；又，藉由S b、C a、S r添加 ，改良合金組織，使結晶粒徑尺寸微細化，能夠提升高 溫潛變性能。 若根據申請專利範圍第2項、第5項的發明’由於 對AZ91系合金，添加Si、RE、Zr至成形性沒有大變化 的程度而成的合金，作爲基質合金，所以可以防止室溫 的強度特性降低，並維持成形性。又，這些元素’會在 析出於粒界而成爲弱點的原因之Θ相的間隙內析出’而 分開/?相，所以能夠確實地提升高溫潛變性能° -20- 200540281 (17) 【圖式簡單說明】 第1圖係表示將Sb、Ca和Sr添加在AZ91合金中所 得到的合金的熔點特性的圖。 第2圖係表示將ca、Si、RE、Sr、Zr各添加1重量 %在A Z 9 1合金中所得到的合金的熔點的圖。 .第3圖係表示將微細化劑添加在AZ9 1系合金中的添 加效果的圖。 第4圖係表示將Sr添加在AZ91SbCa合金中的添加 效果的圖。 第5圖係表示在本發明的一實施形態中，將Sb、Ca 和Sr添加在AZ91系合金中的比例的範圍的圖。 第6圖係表示AZ91合金和AZ91SbCaSr合金的結晶 粒徑尺寸比的變化動態的圖。 第7圖係表示合金鑄錠的組成的圖。 第8圖係表示合金的充塡率動態的圖。 第9圖係表示合金的室溫拉伸強度的動態的圖。 第1 〇圖係表示合金的室溫拉伸特性的動態的圖。 第1 1圖係表示合金的高溫應變速度和流動應力之間 的關係的動態的圖。 第1 2圖係表示合金的高溫應變速度和潛變拉伸率之 間的關係的動態的圖。 第1 3圖係表示在各種鎂合金中的高溫潛變速度和應 力之間的關係的圖。 第1 4圖係表示潛變試驗的試驗條件的圖。 -21 - 200540281 (18) 第15圖係表示在耐蝕性試驗中所使用的原料鑄錠的 組成的圖。 第1 6圖係表示耐蝕性試驗的結果的圖。 第1 7圖係表示被記載於習知技術文獻中的合金特性 的比較內容的圖。200540281 (1) IX. Description of the invention [Technical field to which the invention belongs] The present invention relates to a magnesium alloy that is lightweight and has a high specific rigidity, and particularly relates to a magnesium alloy for die-casting and a magnesium die-casting product using the magnesium alloy for die-casting [prior art ] Among the most widely used alloys, magnesium alloys are the lightest and more rigid alloys. Mg alloys for casting are used in portable electric appliances, including notebook computers and mobile phones. AZ91 alloy. This AZ9 1 alloy is excellent in strength, corrosion resistance, and formability. It is widely used for die casting as a well-balanced casting alloy, but it is not suitable for those requiring high tensile, bending, and heat resistance. For mechanical and automotive applications. Therefore, for these applications, an AM 60-based alloy or an AM 50-based alloy which reduces the amount of A1 to improve the stretchability is usually used. In recent years, as the requirements for weight reduction of automobile parts have increased and at the same time Mg alloying has been applied to the covers that are closer to the engine, the development of new alloys that impart heat resistance has been actively carried out (for example, refer to Patent Document 1). The alloy according to this conventional technology is an alloy made of modified AM50 alloy or AM60 alloy; the weight is A1: 2-9. / 〇, S r: 0.5 to 7 weight ° / 〇 As a substrate, it is desirable to prepare A1 ·· 4 to 6% by weight, A1: 4.5 to 5.5% by weight, and Zn: 0.35% by weight /. The following (AM alloy standard). Further, regarding a comparison between an alloy made by the aforementioned conventional technique and an AZ-based alloy, Example -5-200540281 (2) As described in Non-Patent Document 1. Fig. 7 is a diagram showing comparative contents described in this document. Furthermore, Patent Document 2 shows an example of attempting to improve characteristics by using Si, RE, and the like; as an example, it is shown that RE: 0 · 1 to 4% by weight, Si: 0.7 to 5% by weight, and Mη: 1% by weight or less, Zr: 1% by weight or less, Ca: 4% by weight or less, A1: 10% by weight or less, Zn: 5 weight percent or less, and Ag: 5% by weight. /. Examples of constituent components are given below. [Patent Document 1] Japanese Patent Application Publication No. 2003-517098 [Patent Literature 2] Japanese Patent Application Publication No. 9-316586 [Non-Patent Literature 1] Pegureryutu and Balil co-authored "Development of Creep Resistant Mg-Al-Sr Alloys" Magnesium Technology 2001 (TMS) [Summary of the Invention] • (Problems to be Solved by the Invention) However, the aforementioned conventional alloys (alloys modified from AM50 alloy or AM60 alloy) have the following problems. The lower part of FIG. 17 shows an example of the alloy of the conventional technique (hereinafter referred to as a conventional alloy). Compared with the AZ91 alloy, the tensile strength at room temperature (normal temperature) is approximately 15% lower. Although the tensile strength at 175 ° C is improved by about 7%, the tensile strength at room temperature and 17 ° C is low. The creep properties, etc., are indeed improved, but when the material is actually used, it is not exposed to the physical properties at room temperature because it is exposed to a high temperature environment from room temperature to 175 ° C. The aforementioned conventional technique does not take into consideration -6-200540281 (3), and cannot prevent the reduction in strength at room temperature. An object of the present invention is to provide a magnesium alloy for die casting and a magnesium die casting product using the magnesium alloy for die casting, which does not cause a decrease in the strength at room temperature and can improve the high temperature creep properties. (Means for Solving the Problems) * In order to achieve the aforementioned object, the magnesium alloy for die casting according to the first invention is characterized by 6.0 to 11.0% by weight of aluminum and 0.1 to 2.5% by weight of zinc. At least one of antimony and calcium, and thorium are added to the AZ91-based alloy containing 0.1 to 0.5% by weight of manganese as a crystal refiner. According to the first invention of the present application, the alloy to be a matrix is an AZ91-based alloy containing 6.0 to 11.0% by weight of aluminum, 0.1 to 2.5% by weight of zinc, and 0.1 to 0.5% by weight of manganese. A composition was added with Sb, Ca, and Sr added. By making the matrix an AZ91-based alloy, it is possible to prevent the deterioration of the strength characteristics at room temperature like the AM60-based alloy. In addition, by adding Sb, Ca, and Sr to this AZ91-based alloy as a crystal refinement agent, and improving the alloy structure to refine the crystal grain size, it is possible to obtain a product known for its high-temperature creep resistance and heat-resistant magnesium alloy. AS 2 1 alloy has the same excellent characteristics. As a result, an alloy having an improved high temperature creep property can be realized without causing a decrease in the strength at room temperature. In order to achieve the foregoing object, the magnesium alloy for die-casting according to the second invention is characterized in that AZ91 is already contained in 6.0 to Η · 0% by weight of aluminum, 0.1 to 2.5% by weight of zinc, and 0.1 to 0.5% by weight of manganese. Based alloy, at least one of 0.1 to 1.5% by weight of silicon, 0.1 to 1.2% by weight of rare earth, and 0.2 to 40% by weight of chromium 20052281 (4) to 0.8% by weight are added. The alloy is further added with at least one of antimony and calcium as a crystal refiner, and a saw. With regard to the second invention of the present case, it is an alloy to be a matrix, that is, 6.0 to Π. 0% by weight of aluminum, 0.1 to 2.5% by weight of zinc, and manganese; [~ 0.5% by weight of the so-called AZ91 Series alloy, adding at least one of silicon 0. 1 to 1.5% by weight, rare earth group 0. 1 to 1.2% by weight, and chromium 0. 2 to 0.8% by weight to complete the matrix alloy, that is, adding one side An element that maintains its formability and strength at room temperature and improves its high temperature creep performance. In addition, by using this AZ9 1-based alloy as a crystal micronizing agent and further adding Sb, Ca, and Sr to improve the alloy structure, it is possible to refine the crystal grain size. Different from the first invention of the present case, one of silicon, rare earth, and chromium is added to the matrix alloy side. Will these alloys enter the weak point of the eight-291 series alloy, that is, the grain boundary product? ^ 17 person 112 (cold phase), or, if Ca is added, Al2Ca crystals are generated in the interstices, and these phases are separated, thereby improving the strength. However, if it is added excessively, moldability may be deteriorated. Therefore, it is desirable to add silicon silicon to 1.5% by weight, rare earths 1.2% by weight, and chromium 0.8% by weight. As a result, it is possible to surely maintain the characteristic of the alloy of the present invention, that is, formability, and further improve the thermal creep resistance. The third invention is the first or second invention described above, wherein at least one of antimony 0 to 1.5% by weight and calcium 0.2 to 3 · 5% by weight is added as the crystal micronizing agent, and 缌 0 · 1 to 1.5% by weight, other ingredients are inevitably contained. -8-200540281 (5) In the third aspect of the present invention, the amounts of antimony, calcium, and thallium are added to 0 to 1.5 wt% of antimony and 0.2 to 3.5 weight of calcium. /.缌 0 · 1 ~ 1.5% by weight, it is possible to ensure that the crystal grain size is less than 20 # m, and to obtain the same excellent performance as AS 2 1 alloy, which is known for its high temperature creep properties and heat resistant magnesium alloy. characteristic. As a result, an alloy having improved high-temperature creep properties can be surely realized without causing a decrease in the strength at room temperature. In order to achieve the aforementioned object, the magnesium die-cast product according to the fourth invention is characterized by using a magnesium alloy for die-casting. The magnesium alloy for die-casting is constituted by die-casting, and is 6.0 to 11.0% by weight of aluminum and 0.1 to 2.5% of zinc. AZ91-based alloy containing 0.1 to 0.5% by weight of manganese is an alloy obtained by adding at least one of antimony and calcium and rhenium as a crystal refiner. • In the fourth invention of the present invention, as the alloy used in the magnesium die-casting product, 6.0 to 1.1 wt% of aluminum and 0.1 to 2.5 wt% of zinc are used. / 〇, manganese 0.1 to 0.5% by weight of the so-called AZ91 series alloy, an alloy with the composition of Sb, Ca, Sr added. By making the matrix of the alloy an AZ91-based alloy, it is possible to prevent a decrease in the strength characteristics at room temperature like the AM60-based alloy. In addition, by adding Sb, Ca, and Sr to this AZ91-based alloy, it is used as a crystal refiner that does not impair the effect even if it is remelted for die-casting, does not impair the fluidity of the molten soup, and improves the alloy structure to crystallize. Refinement of the particle size and the same excellent 200540281 (6) characteristics as AS2 1 alloy known for its high temperature creep properties and heat resistant magnesium alloy. As a result, the use of an alloy that does not cause a decrease in the strength at room temperature and an increase in the high-temperature creep property can produce a die-formed product with good formability. In order to achieve the aforementioned object, the magnesium die-cast product according to the fifth invention is characterized by: The magnesium alloy for die-casting is formed by die-casting, and the magnesium alloy for die-casting is made of AZ91 which has been made into 6.0 to 11.0% by weight of aluminum, 0.1 to 2.5% by weight of zinc, and 0.1 to 2.5% by weight of manganese. Based on alloys, at least one of 0.1 to 1.5% by weight of silicon, 0.1 to 1.2% by weight of rare earth group, and 0.2 to 0.8% by weight of chromium is added to refine the crystals. And an alloy of at least one of antimony and calcium, and rhenium. Similar to the second invention, one of silicon, rare earth, and chromium is added to the matrix alloy side. These alloys enter the weak point of the AZ91 alloy, which is the grain boundary product Mg17Al / 3. Phase) or A 12 C a crystals that are generated when Ca is added, and these phases are separated to improve strength. However, if it is excessively added, the moldability will be deteriorated. Therefore, it is desirable to add silicon to 1.5% by weight, rare earth 1.2% by weight, and chromium 0.8% by weight. As a result, the characteristic of the alloy of the present invention, that is, the formability can be reliably maintained, and the heat-resistant creep property can be improved. The sixth invention is the fourth or fifth invention, wherein the magnesium alloy for die-casting is formed by die-casting; and the magnesium alloy for die-casting is used as the aforementioned crystal refiner-10-200540281 (7 ), At least one of 0 to 1.5% by weight and calcium 0.2 to 3.5% by weight is added, and 缌 0 · 1 to 1.5% by weight / °, and other components are inevitable Contained alloy. In the sixth invention of the present invention, 'the amount of antimony, calcium, and thallium added is set to a chain of 0 to 1.5% by weight, a bromide of 0.2 to 3.5% by weight, and a total of 0.1 to 1. 5 重量 ° /. It is possible to reliably set the crystal grain size to 20 # m or less, and it is possible to obtain excellent characteristics equivalent to-A S21 alloy, which is known for its high temperature creep performance and heat resistant magnesium alloy. As a result, the use of an alloy that does not cause a decrease in the strength at room temperature and an improvement in the high-temperature creep property can surely produce a die-cast product. [Embodiment] (Best Mode for Carrying Out the Invention) An embodiment of the present invention will be described below with reference to the drawings. As described above, the inventor of the present invention does not incur room temperature like a conventional alloy, as described above. The concept of reducing the strength and improving the high temperature creep properties is to conduct various reviews on magnesium alloys for die casting and die casting products that improve the high temperature creep characteristics while maintaining the excellent characteristics of the AZ9 1 alloy. In the following, the way of thinking and the results of the review are explained in order. In addition,% in the text means all the weight%. (1) Refinement of crystal grain size First, the inventors of the present invention conducted a review with the objective of improving the characteristics of the AZ9 1 alloy die-cast product 200540281 (8). The crystal grain size of the A Z 9 1 alloy after die-casting was about 40 #m, and the crystal grains were considerably finer compared with the case of the conventional gravity casting of about 200 to 300 / im. Therefore, the crystal micronizer used in the conventional gravity casting is considered unnecessary in the die casting casting. The inventor of the present invention deliberately added a micronizing agent to a die-casting alloy, and tried to perform die-casting with an ingot of this alloy. Among various micronizing agents, such as hexachloroethane, even if the micronizing effect is high, Chlorine gas will occur during the addition; or it will be accompanied by considerable danger in handling like metal Na. In the present invention, Sb, Ca, and Sr are selected as the micronizing agent that is used for die-casting and does not impair the effect even after remelting, and the compound addition is reviewed. Initially, the melting point of the A Z 9 1 alloy and the alloy formed by adding S b 0 · 5% + C a 0 5% + S r 0.5% to A Z 9 1 was measured by the furnace cooling method. From " This result shows that the alloy with Sb, Ca, and Sr added has a slightly lower melting point than the AZ91 alloy (see Figure 1). Regarding other elements, 1% was added to the molten alloy of A Z91 alloy 'to measure its melting point. From this result, it can be seen that ′ together with the addition of a small amount of each element maintains its melting point or decreases (see Figure 2). The respective molten soups were melted again and injected into the molds, respectively. It was confirmed that the fluidity of all molten soups (equivalent to die-casting moldability when applied to die-casting products) was completely satisfactory and was good. As the RE source, MM (Mixed Rare Earth Metal) was used. Next, in the iron coated pot after melting, melt 3kg of AZ91 alloy and keep it at 680 ° C, add the specified amounts of Ca and S r, and then use 200540281 〇) handle spoon 100 g each time It was quickly cast into a tubular metal mold (thickness of the tube wall 3 mm, inner diameter 32 mm 0, and depth 53 mm) which had been warmed to 100 ° C in advance, and a sample was prepared. The sample was cut horizontally in the middle part, and in order to make the crystal grain boundary clear, it was melted at 4 ° C for 2 hours, and then honed to a mirror surface, and then etched with a 6% picric acid ethanol solution. And check with a microscope. The crystal grain size was determined by the slicing method using the crystal grain size measurement method of JIS Steel. 'Figure 3 shows the results of adding Sb and Ca to the AZ91 alloy. From this figure, it can be seen that when antimony is added, the effect is small, but when antimony and calcium are added in combination, the effect is almost the same as that of calcium. Fig. 4 shows an example of adding Sr to the molten soup that has been compounded; using SrO. 6% or more, the crystal grain size becomes 20 // m or less. The same tests were performed on alloys in which Si, RE, and Zr were added in an amount of 0.5 to 1.0% in AZ91 alloy, and almost the same results were obtained in terms of crystal grain size. Although crystals peculiar to Si, RE, and Zr were dispersed, the size of the entire crystal grains did not change. Fig. 5 shows an example of the results of changing the various additions of Sb, Ca, and Sr and examining the relationship between the addition and the crystal grain size. Furthermore, the so-called AZ alloy in this case refers to A Z 9 1 + 0.5% Si alloy, AZ91 + 0.5 ° / 〇RE alloy, and AZ91 + 0.5% Zr alloy in addition to AZ91 alloy. As shown in FIG. 5, it can be seen that when compound addition is performed in the range of Sb0.5%, Ca0.5 to 3.0%, and Sr0. 1 to 1.5%, within the range surrounded by the dotted line, then Can be below 2 0 // m. -13- 200540281 (10) Furthermore, the inventor of the present invention learned from another experiment that the above-mentioned sb and ca 'are not added, but only S b ·· 0 ~ 1.5% and C a: At least one of 0 · 2 to 3 · 5% can achieve the same miniaturization effect as the range enclosed by the dotted line. Therefore, in order to obtain this miniaturization effect, it is sufficient to add at least one of Sb: 0 to 1.5% and Ca: 0.2 to 3.5%, and Sr: 0.1 to 1.5%. The alloy formed by adding Sb, Ca, and Sr to the AZ91 alloy is die-cast. When compared with the AZ9 1 alloy, the crystal grain size of the die-cast product is the same as that of the crystal grains when it is cast in a tubular mold. The diameters are approximately the same. On the other hand, the AZ9 1SbCaSr alloy's crystal grain size ratio relative to the AZ91 alloy is approximately reduced to W3 even under different casting and forming conditions (see Figure 6). Conventionally, as for die-casting products, since the crystal grain miniaturizing agent is considered useless, this is a new idea. As the size of the crystal grains becomes finer, the surface of the grain boundary network is smooth and fine, the material strength is increased, and the thickness of the yS phase precipitated at the grain boundary is reduced. It is a coarse metal that is easily generated in the grain boundary due to corrosion. Since the compounds are not easily formed, the corrosion resistance can be improved. When Si, RE, and Zr are added to an AZ alloy, the strength and corrosion resistance of the alloy are improved. This is equivalent to preventing / 3 from entering the intermetallic compounds at the grain boundary to prevent coarsening. As a result, characteristics are brought. The improvement can be said to be a very similar mechanism. 200540281 (11) (2) Room temperature strength and tensile properties and molten soup fluidity Next, the inventors of the present invention reviewed the AZ91 alloy as described above and the Si, RE, and Zr based on the results of (1). Room temperature strength characteristics and room temperature of alloys added to AZ91 alloys, and alloys further added with Sb, Ca, and Sr (hereinafter 'appropriately referred to as "Sb, Ca, and Sr added alloys") Tensile properties. The alloy ingot shown in Figure 7 was used, and a cold die-casting molding machine was used. The forming temperature (melting furnace temperature) was 650 ° C, and a 1.5 mm thick, B5 size flat test metal mold was used. Form 80 pieces at a temperature of 200 ° C. Five formed plates were divided into three equal parts in the horizontal direction and two equal parts in the vertical direction. Six small pieces were formed, and the density was measured by the water displacement method. Then, the component 分析 and the atomic density recorded in the chemical handbook were analyzed. Table, add up the calculated theoretical density, and calculate the filling rate in the mold. Furthermore, a normal temperature tensile test piece was cut out from 5 pieces of the formed plate, and then the tensile strength and elongation (tensile strength) at room temperature were measured using an English tensile tester (ins tΓ 0 n te ns 丨 1 etester). value). Fig. 8 is a graph showing the filling rate of the test plate after die casting (the average filling rate of the composition of the present invention). From the figure, it can be seen that if Sb, Ca, and Sr are added, the filling rate is improved. Figure 9 shows the room-temperature tensile strength of the die-cast product. Also, "combined" indicates the measurement result after the die-casting test piece was melt-treated at 40 ° C for 2 hours. As shown in the figure, in the case of 'as-cast', Sb, Ca, and Sr added alloys are approximately 7% higher than AZ91 alloys. In addition, if the "AZ91 alloy" is melt-treated, the strength is reduced ", and according to the results of -15-200540281 (12) observed in the test piece, bubbles are scattered, which is considered to be a cause of lowering the physical properties and lowering the filling rate. On the other hand, according to the alloy according to the embodiment of the present invention to which Sb, Ca, and sr are added, even if the alloy is subjected to a melt treatment, the strength does not decrease, and no bubbles are observed. The elongation is shown in Fig. 10. The Sb, Ca, and Sr addition alloys are substantially the same as the AZ91 alloy. It can be seen that if Sb, Ca, and Sr are added to the AZ91 alloy, there is no air bubble entanglement during die-casting, and the tensile strength is improved by increasing the filling charge rate and the die-casting formability. On the other hand, for the AZ91 alloy on the side to be added, the inventor of the present invention also reviewed each component. As for A1, if it is lower than 6%, it is known that the above-mentioned room temperature tensile strength improvement effect cannot be obtained. . Therefore, in order to improve the tensile strength at room temperature, it is judged that the content ratio of A1 is preferably 6% or more. As for the effects of the addition of S i 'RE and ZΓ, the aforementioned upper limit is determined by visually checking the melt fluidity as described above. When these upper limits are exceeded, the viscosity increases, and it has been confirmed that it will adversely affect the melt fluidity. The lower limit 値 'is the room-temperature tensile strength of the added alloy, and the lower limit 値 is the amount by which the strength is improved. Figure 11 shows the relationship between the amount added at this time and the tensile strength at room temperature. Add improvement, average + 12%. Based on the above results, the inventors of the present invention have judged that A 1: 6 to 1 1 · 0%, Z η: 0 · 1 to 2 · 5%, M η: 0 · 1 to 0 · 5% The AZ91 alloy is an alloy obtained by adding a predetermined amount of Si, RE, and Zr, and is suitable as a matrix alloy. These matrix alloys are collectively referred to as AZ91 series 200540281 (13) alloys, and the respective graphs also show the average 値 of the entire alloy. (3) High-temperature creep characteristics Next, the inventors of the present invention reviewed the high-temperature creep characteristics of Sb, Ca, and Sr-added alloys based on the results of (1) and (2) above. From five die-cast products, test pieces were cut out, and a constant speed type high temperature creep tester was used to obtain creep data at 175 ° C. In addition, for comparison purposes, the same measurement was performed on a general AZ91 alloy or other AZ-based alloys. Figures 11, 12 and 13 show the results of the constant temperature method high temperature creep test at 175 ° C. Figure Π shows the relationship between strain rate and flow stress. Compared with the AZ91 alloy, the Sb, Ca, and Sr added alloy of this embodiment obtained by adding Sb, .Ca, and Sr to the AZ91 alloy has an increase in flow stress of 15 to 30% at various strain rates. Higher latent resistance. Figure 12 is data showing creep elongation. For AZ61 alloy and A Z91 alloy, due to the difference in creep speed, the elongation rate may be less than 25%. In contrast, Sb, Ca, and Sr added alloys, regardless of the strain rate, the elongation rate is 3 5% or more. Fig. 13 is a graph obtained by describing these results on a graph in the database of the Japan Magnesium Association for comparison with other alloys. The Association's measurement method is the constant stress method. No matter which method is used, the principle is to evaluate the same physical properties. In addition, the literature data of other alloys at 17.5 t: are also shown at once. Furthermore, in the figure, "Mercer" means that according to reference -17- 200540281 (14) "WEMercerII" Magnesium Die Cast Alloys for Elevated Temperature Applications', SAE Paper No. 900788, SAE Warrendale, PA, USA, 1 990. "Nagaoka Technological University" means that according to the literature "Houxian Kangyu, Kazutaka Takaharu, Takeda Hideta:" Microstructure and High Temperature Strength Properties of Mg-Zn-Al-Ca-RE Alloy Die-casting Materials " Light Metal Society's 103rd Autumn Conference Speeches 槪 Collection! 5-1 16, P. 3 7 5 ". • The measurement conditions of the inventor's creep test and the Japanese Magnesium Association creep test shown in Fig. 13 are shown in Fig. 14. The ZACE054 1 1 alloy of Nagaoka Technical University in Figure 13 crosses AS21 and stands. The other materials are about Mercer's basic alloys. You can see the latent resistance of AS41, AS21, and AS42, which are the heat resistant magnesium alloys. The Sb, Ca, and Sr added alloy according to this embodiment is located on the extension line of the creep curve of the AS21 alloy, and the current creep resistance can be considered to be equal to A S 2 1. That is, it was found that by adding S b, Ca, and S r to the A Z 9 1-based alloy, an alloy having a high temperature latent property of A S 2 1 or higher with high high temperature latent properties can be obtained. In addition, the inventors of the present invention, as described above, did not review the addition amounts of Sb, Ca, and Sr, but also reviewed the effect of the composition of the AZ91-based alloy on the added side on the tensile strength at room temperature; If the content ratio of A1 exceeds 11% by weight, the deterioration of elongation will exceed 1%. Therefore, in order to increase the high temperature latent property, it is appropriate to set the content ratio of A1 to 11% by weight or more. 200540281 (15) (4) Corrosion resistance AZ 9 1 alloy is an alloy with excellent corrosion resistance among M g alloys; the alloy of this embodiment is a matrix alloy in which Si, RE, and Z are added to AZ 9 1 alloy. r, and as a micronizing agent, new elements sb, Ca, and Sr are added. If the uranium resistance is greatly deteriorated as a result, it is not practical. Therefore, the inventors of the present invention performed a salt water spray test on the AZ-based Sb, Ca, and Sr additive alloys of the present embodiment and a normal AZ91 alloy to confirm the corrosion resistance. The salt spray test is carried out as follows. First, as the raw material ingot, the ingot shown in Fig. 15 was used. Regarding die-casting, the test alloys A and B were die-casted at a forming temperature (melting furnace temperature) of 620 ° C, 650 ° C, and 680 ° C, and formed into a plate shape. As a sample shape for the salt spray test, the thickness of the formed plate was set to 0.7 mm, and a shape of 95 mm x 130 mm was cut out. As a pretreatment condition, a chemical conversion treatment was not performed, but the surface was wiped with acetone. As a test method, a corrosive saline spray tester (manufactured by Siiga Tester Co., Ltd.) was used, and the temperature in the test tank was set to 35 ° C and the spray pressure was set to 0.098 MPa (Ikgf / cm2). After continuous spraying under this condition for 2 hours, the sample was rinsed with running water, left for 16 hours, and evaluated by visual inspection in five stages: "Almost no corrosion-~ 5", "Slightly corrosive + ~ 4", "Corrosive + "~ 3", "All-round corrosion + + + ~ 2", "All-round significant corrosion ~ 1" to evaluate the degree of corrosion occurrence. Figure 16 shows the results. As shown in FIG. 16, according to the AZ91 series of the present embodiment, 0.5% each of Sb, Ca, and Sr is added. 200540281 (16) is the aforementioned "corrosion ~ 3", and the normal AZ91 alloy is also "corrosive 1" Worm ++ ~ 3 ". In other words, regarding the corrosion resistance, there is no large difference between the two types of alloys. 'It is understood that the Sb, Ca, and Sr-added alloys of the present embodiment also have corrosion resistance substantially equal to that of ordinary AZ alloys. As described above, if a magnesium alloy for die-casting can be obtained according to this embodiment, while ensuring good die-casting formability and corrosion resistance, it has room temperature tensile strength equivalent to that of AZ91 alloy, and has high temperature creep J properties. . The alloy according to this embodiment is used as a table covering a range from room temperature to high temperature for applications such as transmission covers, oil pans, or automotive air-conditioning piston parts housings, airbag covers, and hoods that can reduce weight. Sharpened articles' are particularly useful. [Effects of the invention] According to the inventions in the first to sixth scopes of the patent application, the composition of S b, C a, and S r is added to the AZ 9 1 series alloy to make it possible to prevent the reduction of the strength characteristics at room temperature In addition, by adding S b, Ca, and S r, the alloy structure is improved, the crystal grain size is refined, and the high temperature creep performance can be improved. According to the inventions in the second and fifth claims of the scope of patent application, 'Si-RE alloy is added to AZ91 series alloy to the extent that there is no significant change in formability as a matrix alloy, so it can prevent room temperature The strength characteristics are reduced and formability is maintained. In addition, these elements "separate in the gap of the Θ phase which is a cause of weakness due to the grain boundary" and separate /? Phase, so it can reliably improve the high temperature creep performance ° -20- 200540281 (17) [Schematic Brief description] Fig. 1 is a graph showing the melting point characteristics of an alloy obtained by adding Sb, Ca, and Sr to an AZ91 alloy. Fig. 2 is a graph showing the melting point of an alloy obtained by adding 1% by weight of each of ca, Si, RE, Sr, and Zr to the A Z 9 1 alloy. Figure 3 is a graph showing the effect of adding a finer to an AZ9 1-based alloy. Fig. 4 is a graph showing the effect of adding Sr to the AZ91SbCa alloy. FIG. 5 is a diagram showing a range of a ratio of adding Sb, Ca, and Sr to an AZ91-based alloy in one embodiment of the present invention. Fig. 6 is a graph showing the dynamic change of the grain size ratio of the AZ91 alloy and the AZ91SbCaSr alloy. Fig. 7 is a view showing the composition of an alloy ingot. Fig. 8 is a graph showing the filling rate dynamics of the alloy. Fig. 9 is a graph showing the dynamics of the tensile strength of the alloy at room temperature. Figure 10 is a graph showing the dynamics of the tensile properties of the alloy at room temperature. Fig. 11 is a graph showing the relationship between the high-temperature strain rate and the flow stress of the alloy. Figure 12 is a graph showing the dynamics of the relationship between the high-temperature strain rate and the creep elongation of the alloy. Figure 13 is a graph showing the relationship between the high temperature creep rate and the stress in various magnesium alloys. FIG. 14 is a view showing test conditions of a creep test. -21-200540281 (18) Figure 15 shows the composition of the raw material ingot used in the corrosion resistance test. FIG. 16 is a graph showing the results of the corrosion resistance test. Fig. 17 is a diagram showing a comparison of alloy characteristics described in the conventional technical literature.
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